AI is an avian acute contagious symptom caused by type A influenza virus. The affected animals include geese, chickens, ducks, pigeons and some wild birds. The research on contagious diseases has indicated that AIV (Avian Influenza Virus) is highly pathogenic and contagious. AI was defined by World Organization for Animal Health as a type A infection, also known as fowl plague or European plague. There are three types of AI in relation to the pathogen. These include highly pathogenic, low pathogenic and non-pathogenic. No obvious symptoms were caused by non-pathogenic AI. However, some virus antibody was generated in the infected birds. The symptoms caused by low pathogenic AI included marginal respiratory symptom, reduced food intake, reduced egg production, and a few deaths. The highly pathogenic AI could cause the most serious symptoms with a very high death rate. Humans have not yet had effective methods for prevention and treatment of high pathogenic AI, which was found in 1878. Sterilization, separation and flock slaughtering were applied to prevent further spreading. The infected flock had an extremely high death rate which brought serious financial loss.
Naturally, the correlation between AI and human flu happened through intermediate hosts such as pigs, horses, dolphins, and other mammals. However, the antigenic characteristics of the highly pathogenic AIV changed frequently, which was also called antigenic shift and antigenic drift. In addition, its intermediate hosts increased continuously. The highly pathogenic AIV nowadays could infect humans directly. The first case of inter-species infection was in Hong Kong, China, in 1997, and again on China's mainland and Hong Kong in 1999. It was induced by H9N2 AIV and caused some mortality. It broke the rule in which human and other mammals could only be infected by H1, H2, and H3 influenza virus. H5 and Hg are the newest members of the influenza virus family, which bring new topic for public health. Avian Influenza has broken out in many countries and it has become a major threat to the human health and the safety of global economy.
H1, H2, and H3 were the only influenza virus's found in humans for a long time. All the research, vaccines, and anti-viral medications were aimed towards these three viruses. Human beings had neither immunities nor effective medications against the new outbreak of H5, H9, and H7. Serious symptoms, including fever, muscle soreness, and chills, could be caused in humans by highly pathogenic AIV infections. Its complications could even cause death.
The current major medications for anti-influenza virus include neuralminidase inhibitors (such as Zanamivir, Oseltamivir, etc.), ion channel blockers (such as Amantadine and rimantadine), and nucleotide medications (such as tribavirim, that is, ribavirin or virazole). Ion channel blockers were considered as the best medications for prevention and treatment of influenza viruses.
However, the above mentioned medications have shown limitations:
(1) The neuralminidase inhibitors could effectively restrain type A and B influenza viruses. However, it is relatively expensive, which limits its extension. For example, Tamiflu made in Roche Pharmaceutical Corp. was also called Oseltamivirphosphat, i.e., phosphate of Oseltamivir ((3R,4R,5S)-4-acetylamino-5-amino-3(1-ethylpropoxy)-1-cyclohexene-1-carboxylic acid ethyl ester, with CASRN of 196618-13-0) with CASRN of 204255-11-8. This medicine should be taken twice daily with a dosage of 75 mg each time. Thus 60 RMB was needed per day for medicine. 300 RMB was required for one 5-day treatment phase. Furthermore, Roche Pharmaceutical Corp. refused to release the patent for Tamiflu even after 2017, citing justifications such as the complexity of production and maintaining high quality standards. Thus the production of Tamiflu was in short supply.
However, significant side effects have been found with Tamiflu, including hallucinations, abnormal behaviors and other psychological and neural symptoms. Drug resistance has also been observed in some of the patients.
(2) Ion channel blockers could effectively resist type A influenza virus. However, it is poisonous to the nervous system and could induce drug resistance if taken for a long period of time. It also has no effect on type B influenza virus.
(3) Tribavirin (virazole) could effectively treat the infection caused by RNA and DNA viruses. However, this compound has teratogenic effect which limits its application in clinical practices.
In order to find effective and safe treatment for influenza viruses, many scientists turned to Chinese traditional herbs for help. For example, a Chinese traditional medicine composition which could prevent chicken, duck avian influenza, was introduced in article CN200510011432.3 from Huanan Agricultural University. However, this Chinese traditional medicine composition was not very effective in avian influenza treatment, and thus it cannot meet the requirement for inhibiting the outbreak of AI.
Therefore, a safe, effective, inexpensive medicine which could not only prevent but also treat avian influenza is in great need.